A blast shutter or blast door were a feature of the cockpit windows of Class F shuttlecraft and Danube-class runabouts that could be closed to protect the inhabitants from external threats.
In 2374, after the USS Rubicon entered a subspace compression anomaly, Chief O'Brien closed the blast shutters due to a rise in the phenomenon's gamma radiation. (DS9: "One Little Ship")
Phoenix-class vessels were equipped with forward blast doors over the bridge windows. (PIC: "The Next Generation")